Xenopus vocalizations are controlled by a sexually differentiated hindbrain central pattern generator

Area of Science:

• Neuroscience
• Animal Behavior
• Bioacoustics

Background:

• African clawed frogs (Xenopus laevis) exhibit rhythmic, sexually distinct vocalizations crucial for mating.
• Vocal behavior is regulated by a sexually dimorphic central pattern generator (CPG).

Purpose of the Study:

• To investigate the neural mechanisms underlying Xenopus vocalizations.
• To determine the role of androgens in shaping sexually dimorphic vocal patterns.

Main Methods:

• Eliciting fictive vocalizations from in vitro brain preparations of Xenopus laevis.
• Utilizing serotonin application and electrical stimulation to activate the vocal CPG.
• Examining vocal patterns in testosterone-treated female frog brains.

Main Results:

• Male and female Xenopus brains produced distinct fictive vocal patterns, including a common release call.
• Testosterone treatment in females induced male-specific vocal patterns, suggesting androgen-dependent gain-of-function.
• The vocal CPG is located in the brainstem and appears conserved across sexes.

Conclusions:

• Xenopus possess a sexually undifferentiated release call pattern generator.
• Androgen exposure enables the expression of male-specific calls while retaining the ancestral pattern.
• Serotonergic inputs likely modulate vocal activity in Xenopus.